From intermittency to reliability

Many critics of solar energy claim that the industry cannot meet the generating capacity for an ever-increasing demand in electricity — that the increased use of renewable energy in the national grid will threaten reliability and a utility’s obligation to provide always-on base load power. However, the efficiency of renewables during peak demand and the combination of sources used to provide always-on electricity, prove that renewables have a place in our electrical grid.

Solar is an intermittent energy source — it does not produce energy when the sun is not shining and storage batteries to hold the sun’s energy when the sun in unavailable can add unwanted cost to a project, and therefore are not widely used. Intermittent sources cannot provide a baseload generation capacity for the national grid that is constantly supplying a flow of energy for a utility’s customers. Therefore, these intermittent sources are labeled as unreliable

A symphonic electrical grid

However, the electrical grid runs using a statistical approach to reliability — it is the combination of sources that provide our electrical grid with enough constant, reliable energy for consumers. For example, while one coal plant is running in Virginia, a natural gas plant in Pennsylvania has been turned off. According to Chief Scientist Amory Lovins of the Rocky Mountain Institute,

Reliability is a statistical attribute of all plants on the grid combined…From 2003-2007 coal plants in the U.S. were shut down approximately 12.3% of the time, nuclear plants were shut down 10.6%, and gas-fired plants were shut down 11.8%.

All energy sources have a degree of unpredictability and thus the grid relies on a combination of power plants throughout the U.S., not just a single source. It is similar to an orchestra. Instruments are being played at different times and tones, but it is the combination of instruments and sounds that creates a symphony.

On July 17^th, temperatures forced a Southern utility to send its large energy-consuming customers a notice to decrease its energy use in order to prevent brownouts and/or blackouts. If that utility had access to more solar power, perhaps they never would have had to send out that notice.

Renewables add to the grid’s generating capacity, increase the reliability of electrical flow during peak demand (solar is naturally most efficient during peak demand mid- to late-afternoon) and have proven to decrease the cost of peak demand generation in solar-friendly regions. This could prove especially revalent in Virginia, a state that imports approximately 34% of its energy needs. An increase in renewable generation will provide our electrical grid with a more reliable energy flow, a stronger orchestra.

Room for renewables

Not only can renewables add more reliability to the grid, most dramatically during peak demand, but there is also room for a lot more renewable generation than we are experiencing today.

As recent study released in June 2012 by the National Renewable Energy Laboratory reports,

Renewable electricity generation from technologies that are commercially available today, in combination with a more flexible electric system, is more than adequate to supply 80% of total U.S. electricity generation in 2050 while meeting electricity demand on an hourly basis in every region of the country.

The study provides evidence supporting that renewables, along with other, more familiar forms of generation, can provide reliable energy for consumers and replace fossil fuels as the major source of electrical generation. It suggests that renewable generation has the ability to supply the majority of our energy needs, as opposed to the lackluster 3.6% it generates today.